#     Copyright 2020, Kay Hayen, mailto:kay.hayen@gmail.com
#
#     Part of "Nuitka", an optimizing Python compiler that is compatible and
#     integrates with CPython, but also works on its own.
#
#     Licensed under the Apache License, Version 2.0 (the "License");
#     you may not use this file except in compliance with the License.
#     You may obtain a copy of the License at
#
#        http://www.apache.org/licenses/LICENSE-2.0
#
#     Unless required by applicable law or agreed to in writing, software
#     distributed under the License is distributed on an "AS IS" BASIS,
#     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#     See the License for the specific language governing permissions and
#     limitations under the License.
#
""" Subscript related code generation.

There is special handling for integer indexes, which can be dealt with
much faster than general subscript lookups.
"""

from nuitka import Options
from nuitka.Constants import isIndexConstant

from .CodeHelpers import (
    generateChildExpressionCode,
    generateExpressionCode,
    generateExpressionsCode,
    withObjectCodeTemporaryAssignment,
)
from .ErrorCodes import getErrorExitBoolCode, getErrorExitCode


def _decideIntegerSubscript(subscript):
    if subscript.isExpressionConstantRef():
        constant = subscript.getConstant()

        if isIndexConstant(constant):
            constant_value = int(constant)

            if abs(constant_value) < 2 ** 31:
                return constant_value, True

    return None, False


def generateAssignmentSubscriptCode(statement, emit, context):
    subscribed = statement.getSubscribed()
    subscript = statement.getSubscript()
    value = statement.subnode_source

    subscript_constant, integer_subscript = _decideIntegerSubscript(subscript)

    value_name = context.allocateTempName("ass_subvalue")

    generateExpressionCode(
        to_name=value_name, expression=value, emit=emit, context=context
    )

    subscribed_name = context.allocateTempName("ass_subscribed")
    generateExpressionCode(
        to_name=subscribed_name, expression=subscribed, emit=emit, context=context
    )

    subscript_name = context.allocateTempName("ass_subscript")
    generateExpressionCode(
        to_name=subscript_name, expression=subscript, emit=emit, context=context
    )

    old_source_ref = context.setCurrentSourceCodeReference(
        value.getSourceReference()
        if Options.isFullCompat()
        else statement.getSourceReference()
    )

    if integer_subscript:
        _getIntegerSubscriptAssignmentCode(
            subscribed_name=subscribed_name,
            subscript_name=subscript_name,
            subscript_value=subscript_constant,
            value_name=value_name,
            emit=emit,
            context=context,
        )
    else:
        _getSubscriptAssignmentCode(
            target_name=subscribed_name,
            subscript_name=subscript_name,
            value_name=value_name,
            emit=emit,
            context=context,
        )

    context.setCurrentSourceCodeReference(old_source_ref)


def generateDelSubscriptCode(statement, emit, context):
    subscribed = statement.getSubscribed()
    subscript = statement.getSubscript()

    target_name, subscript_name = generateExpressionsCode(
        expressions=(subscribed, subscript),
        names=("delsubscr_target", "delsubscr_subscript"),
        emit=emit,
        context=context,
    )

    old_source_ref = context.setCurrentSourceCodeReference(
        subscript.getSourceReference()
        if Options.isFullCompat()
        else statement.getSourceReference()
    )

    _getSubscriptDelCode(
        target_name=target_name,
        subscript_name=subscript_name,
        emit=emit,
        context=context,
    )

    context.setCurrentSourceCodeReference(old_source_ref)


def generateSubscriptLookupCode(to_name, expression, emit, context):
    subscribed = expression.subnode_expression
    subscript = expression.subnode_subscript

    subscribed_name = generateChildExpressionCode(
        expression=subscribed, emit=emit, context=context
    )

    subscript_name = generateChildExpressionCode(
        expression=subscript, emit=emit, context=context
    )

    subscript_constant, integer_subscript = _decideIntegerSubscript(subscript)

    with withObjectCodeTemporaryAssignment(
        to_name, "subscript_result", expression, emit, context
    ) as value_name:

        if integer_subscript:
            _getIntegerSubscriptLookupCode(
                to_name=value_name,
                subscribed_name=subscribed_name,
                subscript_name=subscript_name,
                subscript_value=subscript_constant,
                emit=emit,
                context=context,
            )
        else:
            _getSubscriptLookupCode(
                to_name=value_name,
                subscribed_name=subscribed_name,
                subscript_name=subscript_name,
                emit=emit,
                context=context,
            )


def _getIntegerSubscriptLookupCode(
    to_name, subscribed_name, subscript_name, subscript_value, emit, context
):
    emit(
        "%s = LOOKUP_SUBSCRIPT_CONST(%s, %s, %s);"
        % (to_name, subscribed_name, subscript_name, subscript_value)
    )

    getErrorExitCode(
        check_name=to_name,
        release_names=(subscribed_name, subscript_name),
        emit=emit,
        context=context,
    )

    context.addCleanupTempName(to_name)


def _getSubscriptLookupCode(to_name, subscript_name, subscribed_name, emit, context):
    emit("%s = LOOKUP_SUBSCRIPT(%s, %s);" % (to_name, subscribed_name, subscript_name))

    getErrorExitCode(
        check_name=to_name,
        release_names=(subscribed_name, subscript_name),
        emit=emit,
        context=context,
    )

    context.addCleanupTempName(to_name)


def _getIntegerSubscriptAssignmentCode(
    subscribed_name, subscript_name, subscript_value, value_name, emit, context
):
    assert abs(subscript_value) < 2 ** 31

    res_name = context.allocateTempName("ass_subscript_res", "int")

    emit(
        "%s = SET_SUBSCRIPT_CONST(%s, %s, %s, %s);"
        % (res_name, subscribed_name, subscript_name, subscript_value, value_name)
    )

    getErrorExitBoolCode(
        condition="%s == false" % res_name,
        release_names=(subscribed_name, value_name),
        emit=emit,
        context=context,
    )


def _getSubscriptAssignmentCode(target_name, subscript_name, value_name, emit, context):
    res_name = context.getBoolResName()

    emit(
        "%s = SET_SUBSCRIPT(%s, %s, %s);"
        % (res_name, target_name, subscript_name, value_name)
    )

    getErrorExitBoolCode(
        condition="%s == false" % res_name,
        release_names=(target_name, subscript_name, value_name),
        emit=emit,
        context=context,
    )


def _getSubscriptDelCode(target_name, subscript_name, emit, context):
    res_name = context.getBoolResName()

    emit("%s = DEL_SUBSCRIPT(%s, %s);" % (res_name, target_name, subscript_name))

    getErrorExitBoolCode(
        condition="%s == false" % res_name,
        release_names=(target_name, subscript_name),
        emit=emit,
        context=context,
    )
